The present invention relates to portable memory devices and methods of using same.
Portable memory devices, sometimes also known as tags, are known in the prior art. U.S. Pat. Nos. 4,658,357, 4,818,855 and 4,857,893 disclose representative types of these devices.
In the known devices, data is transmitted both to and from the device by modulated electromagnetic waves such as radio waves, magnetic waves or laser light. The incoming waves are demodulated by the device and the data is then processed in the circuitry in the device. The device also has the ability to modulate electromagnetic waves with data to transmit the data outside of the device for receipt by different stations.
The devices are battery powered or can have energy storage means which is charged by electromagnetic energy supplied from a station seeking to read data from or send data to the devices.
While some portable memory devices have read-only memories (ROM's) therein which cannot be altered by data from the stations, some of the devices have memory which can store data received from outside the device.
When a device of this type is used in a critical process where the integrity of the data stored in the device is of prime importance, it is clear from the prior art that, heretofore, the devices were anything but secure.